A radar signal processing method includes: extracting a first chirp sequence signal of a first carrier frequency and a second chirp sequence signal of a second carrier frequency from a radar signal received through an array antenna in a radar sensor; generating a first range-Doppler map by performing frequency conversion on the first chirp sequence signal; detecting a first target cell corresponding to a first target in the first range-Doppler map; determining a first ambiguous Doppler velocity of the first target based on first frequency information of the first target cell; determining a first range of an unambiguously measurable Doppler velocity through the first chirp sequence signal; estimating second ambiguous Doppler velocities based on the first ambiguous Doppler velocity and the first range; and determining a Doppler velocity of the first target by performing partial frequency conversion on the second chirp sequence signal based on the second ambiguous Doppler velocities.